Beverages frequently need to be heated to reduce microbial load and achieve desired shelf life. These beverages have to be further filled hot into containers (e.g., container made from polyethylene terephthalate (PET), or glass bottles and/or aluminum cans) and sealed so as to eliminate microbial contamination, again for a desired shelf life of the finished product-container combination. These containers then need to be cooled down to below about 100° F. to reduce product degradation, to allow for application of labeling to the containers, and for extended storage during warehousing at the manufacturing facility, and for extended storage during shipping, warehousing at distributor and eventually at customer facilities and/or consumer homes prior to eventual consumption. It is also useful to cool containers down to below about 100° F. at the manufacturing facility so that label can be applied to the containers.
Thus, the product itself is filled hot, and sealed in containers, and the product's heat serves to thermally process the “product-container” unit for required shelf life, sensory properties and control of microbial organisms present in an industrial food processing operation. This “hot-fill” process is common in the industry. The “product-container” unit has to be cooled down from filling temperatures, i.e., around 165° F.-200° F. down to below 70 to 105° F. for downstream operations of labeling, storage and transport. Conventional practice is to cool these containers in a forced convection moving belt cooler, wherein the containers travel countercurrent under a spray of cooling water. This cooling water picks up the heat from containers and rejects it at a cooling tower, as is common in industrial practice. Massive amounts of energy and water (via evaporation, etc.) are rejected at the cooling tower.
For example, filled containers made from PET or glass bottles, and or cans are typically cooled from 175°+/−25° F. ranges down to 90°+/−20° F. ranges by spraying re-circulating water over a bed of containers traveling on a moving belt. An example of a conventional system 100 having a container or bottle cooler 102 is illustrated in FIG. 1. In bottle cooler 102, the beverage containers and their contents are cooled. To obtain this cooling, a first water stream 104 having a temperature T1 (e.g., in the range of about 70° F.-95° F., such as 85° F.), is supplied to bottle cooler 102, where it is sprayed, becomes heated, and exits bottle cooler 102 as second water stream 106 having a temperature T2 that is greater than T1. For example, T2 can be in the range of about 80° F.-115° F., such as about 100° F. Second water stream 106 is then sent to heat exchanger 108, where it is cooled back to temperature T1 and exits heat exchanger 108 as first water stream 104. This cooling of second water stream 106 is accomplished at heat exchanger 108 by third water stream 110 that is supplied by cooling tower 112. Third water stream 110 enters heat exchanger 108 at a temperature T3 (e.g., 70°-94° F.), and exits as fourth water stream 114 at a temperature T4 (e.g., 75°-109° F.). These temperatures depend upon the size, content and flow rate of containers and the flow rate of spray water 104 and cooling tower water 110. In conventional practice, to make the size of the container cooler manageable, a higher temperature gradient between the container temperature and the spray water temperature is maintained. This is achieved by having high flow rates for streams 104 and 110. Please see curves “C” and “D” in FIG. 6.
In a typical cooling tower, water pumped by pump 111 from the tower basin 115 is the cooling water routed through the process coolers or heat exchangers (such as heat exchanger 108) in an industrial facility. The cool water absorbs heat from the hot process streams which need to be cooled, and the absorbed heat warms the circulating water. The warm water returns to the top of the cooling tower and trickles downward over the fill material (not shown) inside the tower. As the water trickles down, it contacts ambient air rising up through the tower either by natural draft or by forced draft using large fans (not shown) in the tower. That contact causes a small amount of the water to be lost as windage 116 and some of the water 118 to evaporate. The heat required to evaporate the water is derived from the water itself, which cools the water back to the original basin water temperature and the water is then ready to recirculate. The evaporated water leaves its dissolved salts behind in the bulk of the water which has not been evaporated, thus raising the salt concentration in the circulating cooling water. To prevent the salt concentration of the water from becoming too high, a portion of the water is drawn off for disposal (120). Fresh water makeup 122 is supplied to the tower basin 115 to compensate for the loss of evaporated water 118, the windage loss water 116, and the draw-off water 120. Chemicals may be added to the circulating water to reduce fouling and corrosion. Fresh water makeup 122 is typically water from a municipality (also called “city water”).
Water source 123, for example city water, can be the source of water stream 124, which is sent to water purification unit 126, and exits water purification unit 126 as purified stream 128. Purified stream 128 is then routed to water heater 130 where it is heated (e.g., to a temperature of about 95° F.) and then sent as stream 132 to batch tank 134, where its is blended with other beverage ingredients coming into batch tank 134 as other ingredient stream 136 from ingredient source 137. Alternatively, water stream 124 can be routed first to water heater 130, and then routed to water purification unit 126, where it is then routed as stream 132 to batch tank 134. Stream 132 and stream 136 combine to form blended beverage stream 138, which exits batch tank 134 and is routed to balance tank 140. At balance tank 140, overflow stream 142 (further discussed below) is added to stream 138, and they combine to form stream 144, which exits balance tank 140, and is then sent to heater 146 where it is heated (e.g., to a temperature of about 202° to 207° F.). The heated stream exits heater 146 as stream 148. Stream 148 is routed through holding tube(s) 150 for a sufficient period of time to reduce microbial load and achieve desired shelf life. Stream 148 then exits holding tube 150 and is routed to trim cooler 152. At trim cooler 152, stream 148 is cooled and it exits trim cooler 152 as beverage stream 154 at a temperature (e.g., about 183° F.) that is lower than the temperature of stream 148 that enters trim cooler 152 (e.g., about 202° to 207° F.).
Beverage stream 154 is then used to fill containers at fill station 156. The containers can also be capped at fill station 156. Also at fill station 156, the containers can be inverted for a brief period of time to allow for the heated beverage to sterilize the cap and the inside surface of each container that is not in direct contact with the beverage when the container is in the upright position. After the containers are inverted for a brief period of time, they are reverted back to the upright position and exit fill station 156 as hot beverage filled container stream 158. Hot beverage container stream 158 is then sent to container cooler 102, where the upright containers are placed on a belt and is cooled by spray water. Stream 104 provides water to be sprayed in container cooler 102, which cools the container and the beverages contained therein. For example the containers and the beverages they contain can enter container cooler 102 at a temperature of about 182° F., and exit as beverage filled container stream 160 at a temperature of less than about 105° F., which is a more acceptable temperature for application of labels at a labeling station (not shown).
When filling of containers must be stopped for some reason, such as a temporary mechanical failure of filling equipment, it is undesirable to shut the entire system 100 down because it would take too long a time to start the entire system 100 again and get the temperatures of the various streams back to their desired levels. To avoid a shut down of the entire system 100, a beverage stream 162 having an elevated temperature (e.g., about 182°) can be sent from fill station 156 to divert cooler 164, and then exit as stream 142 having lower temperature (e.g., less than about 110° F.). As previously discussed, stream 142 is routed to balance tank 140.
An example of another conventional system 200 is shown in FIG. 2. In system 200, instead of cooling tower water exiting heat exchanger 108 as stream 114, cooling tower water exits heat exchanger 108 as stream 202. Stream 202 can be maintained in hot water surge tank 203, from which it is routed to water heater 130, where it is used to heat stream 128. Stream 202 exits water heater 130 as stream 204, which has a lower temperature than stream 202. Stream 204 can be maintained in cold water storage tank 205, from which it can be routed back to cooling tower 112 for further cooling. Pump 206 can be used to pump stream 208 from basin 115 to trim cooler 152 to cool stream 148 so that it exits trim cooler 152 as stream 154 having a lower temperature than stream 148. Stream 208 becomes warmer in trim cooler 152, and exits trim cooler 152 as stream 210. Stream 210 is then routed back to cooling tower 112 for cooling. In addition, another pump (not shown) can be used to pump a stream of cooling tower water from basin 115 to divert cooler 164 to pick up heat from stream 162, and then be routed back to cooling tower 112 for cooling, and in this process stream 162 is cooled and exits divert cooler 164 as stream 142.
In a typical container cooler, water is sprayed by a series of consecutive spray heads, wherein stream 104 enters container cooler 102 at an end opposite the end where the containers enter container cooler 102. In a conventional system 100 or 200, streams 104 and 106 have a flow rate in the range of about 800-1,200 gallons/minute (e.g., 874 gallons/minute), and the temperature difference between stream 104 and 106 is kept low in the range of 10 to 15° F. (e.g., stream 104 can have a temperature of 88° F., and stream 106 can have a temperature of about 98° F.).
Conventional systems employ high spray water flow and low temperature rise in the spray water. This correspondingly maintains a large temperature gradient between the container fluid temperature and the spray water temperature. The low spray water discharge temperature limits the amount of heat that can be recovered and used in upstream heating processes, and non-recovered heat is released to the atmosphere at the cooling tower.